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Completed

NCT Number: NCT01777659

Transcutaneous Electrical Nerve Stimulation Improves Vascular Conductance After Coronary Artery Bypass Graft Surgery

The investigators will test the hypothesis that transcutaneous electrical nerve stimulation (TENS) may attenuate peripheral vasoconstriction and to improve blood flow redistribution during handgrip exercise in acute myocardial infarction (AMI) patients after Coronary Arterial Bypass Graft Surgery (CABG).

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Key information

Conditions

Acute Myocardial Infarction Behavior Motor Activity

Age range

48 year–70 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Hospital de Clinicas de Porto Alegre

Porto Alegre, Rio Grande do Sul, 90035-007, Brazil

About this study

Thirty-eight patients will be randomized to a (4 times/day; 30 min/session) for 5-day program of TENS (n = 20) or to placebo-TENS (P-TENS, n = 18) applied on cervical region (C7-T4). Acute sympathetic stimulation by cold pressor test (CPT), Maximal voluntary contraction (MVC), Femoral blood flow (FBF) and femoral vascular conductance (FVC) will be measured as primary outcome pre and post-CABG, even as the 6-minute walk test (6-MWT), Inspiratory and expiratory muscle strength (PImax and PEmax) and β-endorphin as a secondary clinical parameters. In addition, amount of opioid analgesic and pain intensity also will be measured throughout at first 24 hours after CABG (immediately, 6, 12 and 24 hours).

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • a previous history of more than 1 vessel coronary artery disease,
  • lifelong abstinence from tobacco, and
  • formal indication for CABG, according to established guideline.

Exclusion criteria

  • Patients older than 70 years of age, with chronic renal failure, or with unstable angina in the 48 h prior to CABG, moderate or severe valve disease, complex cardiac arrhythmias, stroke, and/or inability to exercise the lower limbs.

Treatment and study plan

Transcutaneous electrical nerve stimulation

Device

Patients will be treated with conventional TENS (ENDOMED 684 Device, ENRAF-Nonius B.V., Rotterdam, Netherlands) for 5 days (4 times/day; 30 min/session) applied on cervical region (C7-T4). TENS intervention was applied as described elsewhere.

Other names: TENS, electrical stimulation

Primary outcomes

  1. Blood flow redistribution - baseline and 5 days later

    Time frame: 1 day

    The ultrasound Doppler system will be equipped with two linear array transducers operating at an imaging frequency of 7- 8 megahertz (MHz). The common femoral artery of the left leg will be insonated distal to the inguinal ligament, 2-3 cm proximal to the bifurcation. Using femoral artery diameter and mean blood velocity (MBF), femoral blood flow (FBF) was calculated as MBF π x (vessel diameter/2)2 x 60. Femoral vascular resistance (FVR) and femoral vascular conductance (FVC) were calculated as (MBP/FBF) and (FBF/MBP * 100 mm Hg), the conductance multiplied by 100 mmHg so that the conductance units will be similar to the units of femoral blood flow (10, 45). The magnitude of reduction FVC (expressed in %) was calculated as vascular conductance during exercise (% change) - conductance at rest (% change) expressed by % of baseline.

Secondary outcomes

  1. Inspiratory and Expiratory Muscle Function

    Time frame: 5 day

    Inspiratory and expiratory muscle strength testing were performed using a pressure transducer (MVD-500 V.1.1 Micro Hard System, Global Med, Porto Alegre, Brazil). Maximal inspiratory (PImax), and maximal static expiratory pressure (PEmax) were measured as previously described.

Other outcomes

  1. Pain Intensity

    Time frame: 5 day

    A visual analog scale (VAS) for assessing current pain intensity will be used to evaluate pain from 0 to 10, where 0 means no pain and 10 indicates severe pain, being applied on the first and on the 5th day after CABG .

  2. Opioid Analgesic Amount

    Time frame: 5 day

    During the first 24 h (immediately, 6, 12 and 24 h) after CABG, the amount of additional analgesic dose (pethidine hydrochloride (HCl) 20 mg, maximum 1 mg/kg/day) was measured for patients in both groups.

  3. β-Endorphin Analysis

    Time frame: 5 day

    Ten milliliters of venous blood will be taken by the phlebotomist. 3 ml of which will be stored in ethylenediaminetetraacetic acid (EDTA) for analysis of a differential white cell count. Seven ml of blood will be divided between an EDTA tube and a lithium heparin (LH) gel tube. These blood samples will be centrifuged and frozen until assayed. β-endorphin was measured by sandwich enzyme immunoassay (ELISA) kit (Phoenix Pharmaceuticals, Inc., USA).

Sponsors and collaborators

Lead sponsor

Hospital de Clinicas de Porto Alegre

Other

Collaborators

  • Hospital Sao Joao
  • University of Brasilia

Registry information

Acronym: TEBCABG

Important dates

Study start
2013
Primary completion
2013
Study completion
2013
First posted
Jan 29, 2013
Registry last updated
Nov 8, 2013

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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